1978 evinrude 115hp no idle/low idle problem

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I have an 1978 Evinrude 115 hp outboard, model 115893c with low idle/ no idle issues. It has always ran under normal conditions, meaning wide open and cruising speeds, but never idling or low speeds. I used the manual to check the ignition system and found I needed a new key switch, so I replaced it thinking that may have something to do with it. Now it only runs with the warm up lever all the way up, doesn't sputter, sounds nice, but once I drop the lever down, it sputters and quits. My compression is the same on all 4 cylinders @ 120-123 psi. I have tested to see if I have good spark using a gap tester that I bought at the auto parts store, and that checks out.

I had the carbs apart twice and rebuilt them. The reason I did it twice is because I thought I missed the low speed screw, but it turns out the carbs don't have that adjustment.

Could it be a timing issue? I have a digital timing light with a tach. I have read the thread for timing in the 'Top Secret' file , and tried it. My last resort is to take it to a mechanic, but I would rather figure it out myself. It's been a fun project, and I don't want to give up.

 

[emdsapmgr]

It is hard for the engine to idle when the idle rpm's are too low. Since yours won't idle at all, probably another issue. When you had the carbs apart, you did not mention removing the idle jets for cleaning and visual inspection. A must. Also, the idle passages in the upper carb body tend to get clogged with dried fuel over the years. Then this happens, the engine won't idle. You need to use some aerosol carb cleaner to clean these passages out. Gumout makes a good carb cleaner, as an example. Aim the straw of the cleaner to the first passage on #1 carb. Note the spray volume coming out the other side of the carb. The do the same passage on carb #2. Compare the outflow volumes. They should be the same. Then go on to the next passage on #1 carb, then onto that same passage on carb #2. Etc till you've done all the carb passages. This is a good test to insure that similar passages flow the same fuel. Your compression is good. The idle rpm's are set on that engine by adjusting the idle timing. Idle rpm's are set at 650-700 rpm's when the boat is floating in the lake, in forward gear. You can't set it on the trailer.

 

[garbage]

Thanks for the reply. I took the carbs apart, and the plugs were not seated properly. I should have read the directions a little closer, I had them in upside down. Lesson learned.